The present invention generally relates to a communication controlling system for mutually reading and writing the contents of memories by a communication means through control signals.
The prior art will be described with reference to the drawings of FIG. 15 to FIG. 21.
FIG. 15 is a diagram showing an example of a system to which the present invention is applied. FIG. 16 is a diagram showing the telegraphic message configuration of D2B as one example of a communication protocol to which the present invention is applied. FIG. 17 is a diagram showing the instruction contents of the control bits within the telegraphic message shown in FIG. 15. FIG. 18 is a diagram showing the configuration of the write memory address assignment telegraphic message by the conventional D2B. FIG. 19 is a diagram showing the configuration of a command assignment telegraphic message by the conventional D2B. FIGS. 20(a)-20(b) are diagrams showing the sequence in a case where the memory reading control and the writing processing of the other terminal are effected by the conventional D2B. FIGS. 21(1)-21(5) are diagrams showing the telegraphic message configuration example by the use of the sequence shown in FIG. 19.
The exchange of the control signals on a control line 151 in FIG. 15 is subjected to the specification of the D2B. The data region 165 on the telegraphic message on the D2B becomes the content which is chiefly divided into the following three portions by the specification of the control bit 163.
(1) Memory address assignment contents PA0 (2) Control command assignment contents PA0 (3) Optional data
The configuration of the data region 165 at the time of the above described "(1) memory address assignment content" becomes an access memory address code 181 as shown in FIG. 18. The configuration of the data region 165 at the time the above described "(2) control command assignment content" has the configuration of an operation code 191 and an operand code 192 as shown in FIG. 19 or the combination of these codes. A case where the terminal A 152 effects the memory control of the terminal B 153 is taken into consideration in such a D2B system. Under the existing circumstances, only the processing of reading the necessary data through the telegraphic message of the write memory address assignment 173 with a control bit 163, and through the read data assignment 172a with a control bit 163 is effected. The terminal A 152 transmits (201) a telegraphic message a with an access memory address code 181 being assigned (211d) to a data region 165 with the master address 161 of the telegraphic message configuration of the D2B shown in FIG. 16 being made a self (terminal A 142) address (211a), the slave address 162 being made the partner (terminal B 143) address (211b), and the control bit 163 being made a write memory address set 193 (211c). Therefore, the terminal A 152 transmits a telegraphic message b with respect to the terminal B 153 with the master address 161 being made a self address (terminal A 152) address (212a), the slave address 162 being made the partner (terminal B 143) address (212b), the control bit 163 being made a read data set 172a/or 172b (212c), the necessary data (212d) from the terminal B153 is read (202) by the synchronous pulse from the terminal B152 to the data region 165 of the above described telegraphic message b by the synchronous pulse from the terminal A 152. Although the write data 175a/or 175b is specified with the control bit 163 as the conventional D2B system is a control type, the concrete directions and so on are not stipulated for, and the data are not easily written with respect to the other terminal.
In order to force the data to be written in the above described system, the data which has a write memory address portion 194 of the partner terminal and a write data store address portion 195 in the operand code portion is required t be read and the demand command 193 must be newly provided. At this time, the terminal A 152 transmits (203) a telegraphic message c with respect to the terminal B 153 with the master address 161 being made a self (terminal A 152) address (212a), the slave address 162 being made a partner (terminal B 143) address (212b), the control bit 163 being made a write command set 174a/or 174b (212c), the operation code (23d) for the above described read processing demand use, the write memory address (213e) and the write data store address (213f) being provided in the data region 165. The terminal B 152 which has received the above described telegraphic message c analyzes the contents of the above described command, sets (214d) in the data region 165 a value of the write data store address 213f within the above described telegraphic message c, transmits to the terminal A 152 (204) a telegraphic message d, with the master address 161 being made a self (terminal B 153) address (214a), the slave address 162 being made the partner (terminal 152) address (214b), the control bit 163 being made the write memory address set 173 (214c), thereafter the terminal B 153 transmits with respect to the terminal A152 a telegraphic message e with the master address 161 being made the self address (terminal B 153) (215a), the slave address 162 being made the partner (terminal A 152) address (215b), the control bit 163 being made the read data set 172a/or 172b (215c) so as to write (205) the data (212d) necessary to the terminal B 153 from the terminal A 152 with the synchronous pulse from the terminal B 153 in the data region 165 of the above described telegraphic message e. But this system has problems in that the sequences become complicated, the management is not easy to effect, because the control system of the reading is used in spite of the writing, the traffic increases by the addition of the number of the telegraphic messages on the transmission passage, and so on.
The control system of the D2B under the existing circumstance has a problem that the writing of the data onto the memory of the other terminal cannot be easily performed with the use of the communication.